Supplementary Figure 8: Model of the sequence of events leading to rhythmogenesis.

Left: Low sensory activity level are insufficient to activate astrocytes and lower [Ca²⁺]_e, thus preventing activation of I_NaP and neuronal bursting. In this condition, NVsnpr neurons work in a sensory relay mode with their tonic output faithfully relaying their tonic input. Right: With food intake and intraoral stimulation, sensory inputs from the periodontal ligament and the jaw muscle spindles increase their activity level and signal the need for rhythmic mastication. This increased activity activates astrocytes and leads to release of the Ca²⁺-binding protein S100β and subsequent decrease of [Ca²⁺]_e. This in turn will activate I_NaP and elicit rhythmic bursting in NVsnpr neurons. The generated bursting frequency and pattern, reflecting the pattern of sensory inputs will then be transmitted to jaw closing and opening motoneuronal pools (masseter (mass) and digastric (dig), respectively).